Hey, I have a JSON response and i need to filter t...

# android

[Vivek Modi]

Hey, I have a JSON response and i need to filter that data in a list. In every JSONObject there are 3 categories in which only one category holds data.

data class CategoryResponse(
        val item: List<CategoryItem>
)

data class CategoryItem(
        val id: Int,
        val Category1: List<ItemOptions>? = null,
        val Category2: List<ItemOptions>? = null,
        val Category3: List<ItemOptions>? = null
)

data class ItemOptions(
        val name: String? = null,
        val url: String? = null
)

I have an enum class, which has 4 enum types

enum class CategoryType(val name :String){
  ALL("ALL"),
  Category1("Category1"),
  Category2("Category2"),
  Category3("Category3");
}

There is a category named ALL, so i need the list of all the data but I don't want any null values, and still want the data that other categories hold.

Example - the list consist of 5 elements 
Desired output:
ALL : list-> [id : 1 , category1 : ”..”] , [id : 2 ,category2 : “..”] , [id : 3 ,category2 : ”..”] , [id : 4 ,category1 : “..”] , [id : 5 ,category3: “.."]   

CATEGORY2: list -> [id : 2 , category2 : “..”] , [id : 3 , category2 : “..”]
(this list may or may not consist of more than 5 elements)
is there any way that this list won’t occupy a lot of memory, or duplicate the objects and could be more efficient.?

[Vivek Modi]

{
"items": [{
"id": "1",
"Category1": [{
"name": "Item ..",
"url": "https:..."
}, {
"name": "Item ..",
"url": "https:..."
}],
"Category2": [],
"Category3": []
}, {
"id": "2",
"Category1": [],
"Category2": [{
"name": "Item ..",
"url": "https:..."
}],
"Category3": []
}, {
"id": "3",
"Category1": [],
"Category2": [{
"name": "Item ..",
"url": "https:..."
}],
"Category3": []
}, {
"id": "4",
"Category1": [{
"name": "Item ..",
"url": "https:..."
}],
"Category2": [],
"Category3": []
},{
"id": "5",
"Category1": [],
"Category2": [],
"Category3": [{
"name": "Item ..",
"url": "https:..."
}]
} ....]
}

[Jeff]

You could change the type of your val Category1: List<ItemOptions>? = null fields to be a single field of

val category: Pair<CategoryType, List<ItemOptions>

or as separate fields

val category: CategoryType
val itemOptions: List<ItemOptions>

Since you have the constraint that only one category will be valid at a time you could flatten it like that.

Then the all / specific could simply be

categoryResponse.items
or
categoryResponse.items.filter{ it.category == CategoryType.Category1 }

[Vivek Modi]

val dataList = CategoryResponse(             listOf(                     CategoryItem(1, listOf(ItemOptions("aa", "ww"), ItemOptions("aa22", "ww22")), null, null),                     CategoryItem(2, null, listOf(ItemOptions("bb", "qq")), null),                     CategoryItem(3, null, null, listOf(ItemOptions("cc", "ee"))),                     CategoryItem(4, null, null, listOf(ItemOptions("dd", "tt"), ItemOptions("dd22", "tt22")))             )     )

[Vivek Modi]

val categoriesList : List<CategoryItem> = dataList.item      categoriesList.filter { list ->         list.Category2 == CategoryType.Category2     }

[Vivek Modi]

it gives error Comparison of incompatible enums 'List<ItemOptions>?' and 'CategoryType' is always unsuccessful on list.Category2 == CategoryType.Category2

[Jeff]

the list inside the filter is a single CategoryItem. You should turn its id into a CategoryType during parsing and then compare it in the filter with the one you want. If you’re going to keep the three types separate in CategoryItem you’ll need to do a map after the filter like .map{ it.Category2 } if 2 is the one you filtered on.

[Vivek Modi]

okk got it

[Vivek Modi]

thanks 😊